Caption: Computer motherboard, close-up. The motherboard is the main circuit board of a computer. It is a printed circuit board (PCB) with copper pathways (orange lines), or traces, that are used to mechanically support and electrically connect electronic components. The large square at left is the socket for the central processing unit (CPU), the main component of a computer. The small square at centre right is the northbridge, which manages data communications between the CPU and motherboard. The wider tracks are for the power lines.